Siemens SINUMERIK 840C - Manual (Page 959)

12 Functional Descriptions 09.95
12.19.3 Interlocks and monitoring
12.19.3 Interlocks and monitoring
Interlocks
In the case of axis-specific interlocks of IKA/TC movements, the current IKA/TC value is
"frozen", it remains applied in static form. In this case, a distinction is made between:
• Direction-dependent interlocks
–
SW limit switch:
After alarm 148* or 152* "SW limit switch" has responded, both normal IPO
movements as well as IKA/TC movements, which lead in a direction away from the
traversing range, are interlocked. In addition, all channels of the mode group assigned
to this axis are aborted.
– HW limit switch
• Direction-independent interlocks:
–
Parking axis
– Axis disable
– Controller disable
– Follow-up mode
All interlocks are cancelled as soon as the cause itself has been eliminated (and not following
a RESET).
If it is necessary to disable the traversing axis from the PLC program or to stop the IKA/TC
movement, then the axial PLC signals "Controller disable", "Follow-up mode", "Axis disable"
and "Parking axis" must be applied.
The axial feed stop and the channel-specific feed stop or override zero can be applied to all
axes in the mode group only via the leading axis or via the channel.
If the axis programmed as the input quantity loses its reference point (e.g. due to parking axis),
then the output quantity is not "frozen", but reduced to zero.
Limit switch monitoring
When IKA/TC is active, the effective machine position of the output quantity axis is always
evaluated when limit switch monitoring is activated:
NC setpoint - IKA/TC value.
The braking ramp is not activated until the SW limit switch is reached so that traversal slightly
beyond the switch (depending on feed) is possible.
When an SW limit switch is reached, alarm 148* "SW limit switch +" or alarm 152* "SW limit
switch -" is always output.
The response of the monitor is dependent on the following factors:
Automatic/MDI mode:
A part program block is always examined prior to traversal for the points at which limit switches
are reached. When the IKA/TI is active, however, it is not possible to identify the path
characteristic in advance. The following situations may occur when this part program is
traversed:
a) With an NC setpoint P
NC
, a machine position P
M
is reached during traversal as a function
of compensation (positive IKA/TC motion).
12–184 © Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)